Not quite sure what you're asking. If you're deviation deadhead qualifies to be booked in First, then you don't have to fill out the upgrade form. Just book first.

If the schedule deadhead is first class, that doesn't mean you can automatically get a first class deviation deadhead. You just get a larger bank because of the first class scheduled deadhead.

The upgrade form is for your deviation deadhead ticket when it only qualifies for coach but you want to fly in first class. You pay the difference out of your own pocket.